The Internet has developed into an important economic, military, academic, and social resource. It is a complex network, comprised of
tens of thousands of independently operated networks, called Autonomous Systems (ASes). A significant strength of the Internet's design, one which enabled its rapid growth in terms of
users and bandwidth, is that its underlying protocols (such as IP, TCP, and BGP) are distributed. Users and networks alike can attach
and detach from the Internet at will, without causing major disruptions to global Internet connectivity.
This dissertation shows that the Internet's distributed, and often redundant structure, can be exploited to increase the security of its
protocols, particularly BGP (the Internet's interdomain routing protocol). It introduces Pretty Good BGP, an anomaly detection
protocol coupled with an automated response that can protect individual networks from BGP attacks. It also presents statistical
measurements of the Internet's structure and uses them to create a model of Internet growth. This work could be used, for instance, to test upcoming routing protocols on ensemble of large, Internet-like graphs. Finally, this dissertation shows that while the Internet is designed to be agnostic to political influence, it is actually quite centralized at the country level. With the recent rise in country-level Internet policies, such as nation-wide censorship and warrantless wiretaps, this centralized control could have significant impact on international reachability.